baseline: Refactor code padding

[chfast]

Use std::make_unique_for_overwrite to create padded code.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.99%. Comparing base (2205fb3) to head (557fa10).

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #517       +/-   ##
===========================================
+ Coverage   29.44%   97.99%   +68.55%     
===========================================
  Files         117      121        +4     
  Lines       10679    12091     +1412     
===========================================
+ Hits         3144    11849     +8705     
+ Misses       7535      242     -7293     

Flag	Coverage Δ
blockchaintests	61.20% <100.00%> (ø)
statetests	61.90% <100.00%> (ø)
statetests-silkpre	23.13% <100.00%> (ø)
unittests	96.57% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
lib/evmone/baseline.cpp	100.00% <100.00%> (+18.18%)	:arrow_up:

... and 108 files with indirect coverage changes